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<html lang="zh-CN">
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    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    <script>
        let red = 0,black = 0,write = 0;
        let red_write = 25;
        let write_black = 31;
        let red_black = 28;
        let sum = (red_write+write_black+red_black)/2;

        red = sum - write_black;
        black = sum - red_write;
        write = sum - red_black;

        alert('红球: '+red +"\n"+'白球: '+write +"\n"+'黑球: '+black);

    </script>
</body>
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